Phased array antennas are known for receiving and/or transmitting signals. In general, phased array antennas may combine signals having relative phase shifts in such a way to produce a radiation pattern. The radiation pattern is typically reinforced in a desired direction (along a main lobe, also referred to herein as a beam) and suppressed in one or more undesired directions. Phased array antennas typically include phase shifters that provide phase-shifts (or delays) to adjacent radiating elements. The phase-shifts (or delays) may be used to tilt the radiated phase front and produce beams in different directions depending upon the phase-shifts applied to the individual elements of the array.
Photonic devices (such as waveguides) are known to be used in phased array antennas as phase shifters. For waveguide phase-shifters, a conventional approach is to create an optically dense medium and change some material parameter of the waveguide to produce a tunable phase shift (i.e., where an amount of phase shift may vary over time). Examples include changing the refractive index of the waveguide through application of an electrical bias (for electro-optically sensitive materials such as LiNbO3) or through application of temperature (for many thermo-optically sensitive semiconductor materials including silicon).